//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++03, c++11, c++14, c++17

// <span>

// template<size_t N>
//     constexpr span(array<value_type, N>& arr) noexcept;
// template<size_t N>
//     constexpr span(const array<value_type, N>& arr) noexcept;
//
// Remarks: These constructors shall not participate in overload resolution unless:
//   - extent == dynamic_extent || N == extent is true, and
//   - remove_pointer_t<decltype(data(arr))>(*)[] is convertible to ElementType(*)[].
//

#include <span>
#include <array>
#include <cassert>
#include <string>

#include "test_macros.h"

void checkCV() {
  std::array<int, 3> arr = {1, 2, 3};
  //  STL says these are not cromulent
  //  std::array<const int,3> carr = {4,5,6};
  //  std::array<volatile int, 3> varr = {7,8,9};
  //  std::array<const volatile int, 3> cvarr = {1,3,5};

  //  Types the same (dynamic sized)
  {
    std::span< int> s1{arr}; // a span<               int> pointing at int.
  }

  //  Types the same (static sized)
  {
    std::span< int, 3> s1{arr}; // a span<               int> pointing at int.
  }

  //  types different (dynamic sized)
  {
    std::span<const int> s1{arr};          // a span<const          int> pointing at int.
    std::span< volatile int> s2{arr};      // a span<      volatile int> pointing at int.
    std::span< volatile int> s3{arr};      // a span<      volatile int> pointing at const int.
    std::span<const volatile int> s4{arr}; // a span<const volatile int> pointing at int.
  }

  //  types different (static sized)
  {
    std::span<const int, 3> s1{arr};          // a span<const          int> pointing at int.
    std::span< volatile int, 3> s2{arr};      // a span<      volatile int> pointing at int.
    std::span< volatile int, 3> s3{arr};      // a span<      volatile int> pointing at const int.
    std::span<const volatile int, 3> s4{arr}; // a span<const volatile int> pointing at int.
  }
}

template <typename T, typename U>
constexpr bool testConstructorArray() {
  std::array<U, 2> val = {U(), U()};
  ASSERT_NOEXCEPT(std::span<T>{val});
  ASSERT_NOEXCEPT(std::span<T, 2>{val});
  std::span<T> s1{val};
  std::span<T, 2> s2{val};
  return s1.data() == &val[0] && s1.size() == 2 && s2.data() == &val[0] && s2.size() == 2;
}

template <typename T, typename U>
constexpr bool testConstructorConstArray() {
  const std::array<U, 2> val = {U(), U()};
  ASSERT_NOEXCEPT(std::span<const T>{val});
  ASSERT_NOEXCEPT(std::span<const T, 2>{val});
  std::span<const T> s1{val};
  std::span<const T, 2> s2{val};
  return s1.data() == &val[0] && s1.size() == 2 && s2.data() == &val[0] && s2.size() == 2;
}

template <typename T>
constexpr bool testConstructors() {
  static_assert(testConstructorArray<T, T>(), "");
  static_assert(testConstructorArray<const T, const T>(), "");
  static_assert(testConstructorArray<const T, T>(), "");
  static_assert(testConstructorConstArray<T, T>(), "");
  static_assert(testConstructorConstArray<const T, const T>(), "");
  static_assert(testConstructorConstArray<const T, T>(), "");

  return testConstructorArray<T, T>() && testConstructorArray<const T, const T>() &&
         testConstructorArray<const T, T>() && testConstructorConstArray<T, T>() &&
         testConstructorConstArray<const T, const T>() && testConstructorConstArray<const T, T>();
}

struct A {};

int main(int, char**) {
  assert(testConstructors<int>());
  assert(testConstructors<long>());
  assert(testConstructors<double>());
  assert(testConstructors<A>());

  assert(testConstructors<int*>());
  assert(testConstructors<const int*>());

  checkCV();

  return 0;
}
